Neither BES nor BIS care about your SIM. Both tie to the PIN of your BB.

If you switch providers you need to delete your BIS account with your former carrier and then set up a new BIS account with your new carrier.

However, by "activation" if you mean Enterprise Activation (BES) then you don't need to activate in either case. Again, BES doesn't care about your SIM. It also doesn't care about which carrier you're with. It's just your PIN that matters.

I bought an unlocked BB Pearl 8100 in Canada. It was a T-Mobile judging by the T-Mobile logo. I was thinking of switching to Rogers and getting signed on to their BB plans with the 6 gigs / $30 we've been hearing a lot about. How the heck would I get in touch with T-Mobile and sort out this one?